Generally a lighting device may be attached to a vehicle, such as a motorcycle, to emit light to an occupant of another vehicle, a pedestrian, and the like. Therefore, various structures have been studied in order to improve viewability of light and appearance design of the lighting device, and to reduce manufacturing cost thereof.
Patent Document 1 (Japanese Patent Application Publication No. 2000-331509) generally discusses a vehicle lighting device in which the number of light-emitting diodes appears to be greater than the actual number when the lighting device is seen from an irradiation side thereof by arranging multiple reflective surfaces in the circumference of a light source attachment surface to which the light-emitting diodes serving as light sources are attached.
When a viewer, such as an occupant of another vehicle or a pedestrian, sees a lighting device attached to a vehicle, the viewer likely sees the lighting device from directions other than the front even if the irradiation direction of the lighting device is directed to a front side of the vehicle body. For example, when a lighting device attached to the front of the vehicle body of a running vehicle is seen by an occupant of another vehicle running in the opposite lane, an angle of the lighting device with respect to the direction of the eyes of the occupant, who is looking straight ahead, of another vehicle sequentially changes. Specifically, as the distance between the two vehicles decreases, such an angle changes from approximately zero degrees where the two vehicles are sufficiently distant to approximately 90 degrees where the two vehicles pass each other. Meanwhile, when a pedestrian sees the lighting device attached to the front of the vehicle body of a stopped vehicle, the direction of the eyes of the pedestrian looking at the lighting device changes in accordance with a distance between the pedestrian and the vehicle. In this manner, the viewer likely sees the lighting device of the vehicle from a diagonal direction having a predetermined angle from the irradiation direction of the lighting device. Thus, the lighting device of the vehicle preferably has a configuration with which the viewability does not decrease even when seen diagonally.
Although the lighting device described in Patent Document 1 can make the number of light-emitting diodes appear to be greater than the actual number when seen from the front by arranging multiple reflective surfaces, Patent Document 1 does not take into consideration how the light-emitting diodes are seen from a diagonal direction.